Gas Chromatography - Applications > Food and Beverage Products > Page 73

Courtesy of Astec Inc.

Figure 47 The Separation of the Enantiomers of Ketamine and its Metabolites Norketamine and Dehydro-norketamine

Ketamine, was recently investigated as a potential drug that would reverse the problem of protein metabolism in AIDS patients. Unfortunately, the determination of the drug distribution in various body fluids by GC analysis was complicated by the presence of two chiral metabolites. The analysis was successfully achieved using a 30 m long, 250 mm I.D. (a Chiraldex G-TA column) operated isothermally at 160˚C using helium as the carrier gas with an inlet pressure of 3 Kg/cm2. The method could separate all 6 enantiomers as their trifluoryl acetyl derivatives as shown in figure 47. The high efficiencies and the general versatility of this stationary phase, that provides strong dispersive and polar interactions, makes it especially useful for the separation of substances with multiple chiral centers and in the presence of metabolites. The use of a 5m retention gap method of injection (see page 19) allowed the direct injection of 7 ml of plasma.

Essential oils (flavors and perfumes) also contain many chiral compounds and one enantiomer may be entirely responsible for a particular taste or odor whereas the complementary enantiomer has an entirely different olfactory effect. It is clear that the use of chiral chromatography can be one of the more useful techniques for the analysis of essential oils. A chromatogram of the essential oil vapor from White Pine leaves is shown in figure 48.